Centrifugal microfluidic devices allow the mixing, sequencing, and control of volumes of liquids. The liquid may be caused to flow through such a device under the action of centrifugal force, by rotating the device about an axis of rotation. Such devices are sometimes known as ‘lab on a disc’ devices.
Processing of liquid in a centrifugal microfluidic device may require the mixing of two or more liquids, for example according to a mixing ratio. It may also be desirable to halt liquid flow through a structure of the device until such a time it is desired to re-start liquid flow.